This invention relates to an optical disk capable of recording information according to the CD format with a greater recording capacity than the currently available 12 cm CD (Compact Disc), an optical disk recording device for recording information on this optical disk and an optical disk reproduction device for reproducing information from this optical disk.
Recording and reproducing time of the currently available CD is about 74 minutes at the maximum. Recording of a longer time can be made by increasing recording density or enlarging the diameter of the CD. Since, however, time information which can be expressed according to the subcode of the CD format is 99 minutes 59 seconds 74 frames at the maximum, some arrangement must be made if one wishes to record information of 100 minutes or more.
For example, Japanese Patent Application Laid-open No. Hei 7-262696 discloses an optical disk in which the recording surface area or portion of a single disk is divided in the radial direction into a plurality of areas each having a constant recording capacity, each divided area is constituted of a lead-in area, a program area and a lead-out area, and, in PSEC, PFRAME or ZERO of Q-channel subcodes in the first lead-in area or in an identification information area which is provided inside of the first lead-in area, identification information for identifying recording states of various information such as the number of the divided areas, number of combined areas, recording capacity of each divided area and TOC of each divided area is recorded. Absolute time information recorded in each divided area starts from a common initial value. A search operation for searching a particular position in a particular divided area is performed on the basis of detection of a position of an optical pickup in the radial direction of the disk (search in the divided area) and detection of absolute time information read from the disk (search in the divided area).
According to the device of the above described publication, since the recording capacity of each divided area is constant, in a case where recording of one program information is finished before the end of the divided area when a plurality of program information are to be recorded in the respective divided areas, there occurs a blank portion in the divided area where no effective information is recorded before a start position of a next divided area (i.e., recording start position for next program information) with the result that the recording capacity of the disk is not fully utilized.
Further, in a case where each divided area has a small recording capacity, identification of each divided area becomes difficult because of poor accuracy in detecting the position of the optical pickup in the radial direction with the result that, during a search operation, a divided area which is different from a designated divided area is erroneously searched. Again, when the optical pickup has erroneously entered an adjacent divided area due to skipping caused by a shock from outside, there is likelihood that such erroneous entering of the optical pickup is not detected and reproduction is continued from that position.
It is, therefore, a first object of the invention to enable full utilization of recording capacity in an optical disk in which the recording surface is divided into a plurality of areas and information is recorded in these divided areas by using absolute time information repeatedly, enable accurate searching of a designated divided area and enable returning of an optical pickup to a correct reproduction position when skipping of the optical pickup has occurred, and also to provide an optical disk recording device for recording information on such optical disk and also to provide an optical disk reproduction device for reproducing information from such optical disk.
There is another problem in the prior art optical disk. Minutes, seconds and frames of address information of the CD format are recorded in 2 digit BCD code and, accordingly, the maximum value of address information is 99 minute 59 second 74 frame. Therefore, even though a larger amount of information can be physically recorded in a single disk, such limitation in address information imposes a limit to an amount of information which can be recorded in a single disk. It is conceivable to use address information overlappingly among respective volumes but such arrangement will impair the function of address information designating only one address resulting in occurrence of trouble in an access operation (i.e., a wrong divided area is accessed in spite of the fact that a correct address is designated).
It is, therefore, a second object of the invention to provide an optical disk in which a large amount of information can be recorded without impairing the function of address information designating only one address, and also providing a reproduction device for reproducing this optical disk.
In case information such as a game software is recorded in a CD-ROM with a higher recording density than a standard recording density determined by the CD format, there will occur a case where it is desired to prevent reproduction of such game software by a standard CD-ROM player. In the past, there has not been such an optical disk or an optical disk reproduction device which can satisfy such demand.
It is, therefore, a third object of the invention to provide an optical disk in which restriction is imposed on information which can be reproduced by a standard reproduction device of the CD format and only the first volume can be reproduced by such standard reproduction device, and also to provide an optical disk reproduction device capable of reproducing all information contained in such optical disk.
For achieving the above described first object of the invention, there is provided an optical disk having a recording surface which is divided in the radial direction of the optical disk into a plurality of volumes each comprising a combination of a lead-in area, a program area and a lead-out area, each of these volumes having a recording capacity which is not constant and being adapted to have absolute position information recorded therein, said absolute position information consisting of time information starting from a common initial value, the lead-in area, the program area and the lead-out area of the respective volumes being adapted to have information of CD format recorded therein, and adapted to have volume number information corresponding to the volume number thereof recorded in a predetermined position of said area.
According to the optical disk of the invention, recording capacity of each volume (i.e., divided area) is not constant (i.e., is variable) and, therefore, by suitably setting the recording capacity of a particular volume in accordance with the capacity of a program to be recorded in this volume, waste of recording capacity can be eliminated and the recording capacity of the disk can be fully utilized. Further, by recording volume number information corresponding to respective volumes in a predetermined position of each format in the lead-in area, program area and lead-out area in the respective volumes, what number of volume is currently being reproduced can be accurately identified by reading out the volume number information from the disk during reproduction of the disk and a search operation can be carried out without mistake even when the recording capacity of the volume is relatively small. Furthermore, since the volume number information is recorded in all of the lead-in area, program area and lead-out area, the volume number can be accurately identified even if skipping of the optical pickup takes place and, therefore, the optical pickup can be restored to a position from which the optical pickup has skipped and reproduction of information can be continued from the restored position.
The volume number information may be recorded in, e.g., ZERO field of Q-channel subcodes. The volume number information may start from 0 or 1. When the volume information starts from 0, the volume number information of the first volume is 0 and, by recording this volume number information 0 in ZERO field, this matches the current CD format and, therefore, reproduction of at least the first volume is possible even in a case where reproduction is rejected unless the ZERO field is 0 in a current CD player or CD-ROM player. In a case where the volume number information starts from 0, control is made during search so as to detect a volume position at which volume number information which is of a value obtained by subtracting 1 from the designated volume number is reproduced. It is also possible to record information indicating presence or absence of the second volume in a main channel of, e.g., the program area of the first volume (for example, such information is recorded in block encoded form in the mode 1 or mode 2 form 1 of the CD-ROM format) and obtain this information when the first volume is reproduced and proceed to the second volume.
By starting the volume number from 1 and recording this volume number 1 in, e.g., ZERO field, it can be identified by merely reproducing the first volume during reproduction that a plurality of volumes are recorded in the disk. When the volume number starts from 1, control is made during search so as to detect a volume position at which volume number information coinciding with the designated volume number value is reproduced.
Final volume identification information indicating that a particular volume is final volume may be recorded, instead of the volume number information or in addition to the volume number information, in a predetermined position of at least the lead-in area of the final volume. By reproducing the final volume, it can be identified that this volume is the final volume whereby a waste operation such as to move the optical pickup radially outwardly after the end of reproduction of the final volume can be eliminated.
By restricting the recording capacity of each of said volumes to less than 100 minutes, current CD players and CD-ROM players can reproduce all volumes if performances of the optical pickup and servo circuit are satisfactory.
When a volume having recording capacity of 100 minutes or more is recorded, by expressing the digit of 10 of minute information in the absolute time information in hexadecimal instead of BCD code, time of 100 minutes or more can be expressed.
There is also provided an optical disk recording device for recording information on the above described optical disk according to the invention.
There is also provided an optical disk reproduction device for reproducing information from the above described optical disk comprising a volume number designation section for designating a volume number, an absolute time designation section for designating absolute time in a volume or information corresponding to the absolute time, a position information extracting circuit for extracting the volume number information and the absolute time information from among information read from the optical disk, and a control circuit for controlling a reproduction position of an optical pickup so that the extracted volume number information will become a value which corresponds to the designated volume number and the extracted absolute time information will become a value which corresponds to the designated absolute time.
According to the optical disk reproduction device, a specific track (e.g., music piece) in a specific volume among the plural volumes of the disk can be designated and searched for reproduction.
For achieving the second object of the invention, there is provided an optical disk having a recording surface on which information prepared in accordance with a CD format is recorded and which is divided in the radial direction of the disk into a plurality of volumes each comprising a combination of a lead-in area, a program area and a lead-out area, a part or all of said volumes having a higher recording density than a standard recording density determined by the CD format, absolute address information recorded in the program area and the lead-out area of each of said volumes being made of address information which continuously increments from an initial value without overlapping among the respective volumes, and address information recorded in the lead-in area of each of said volumes is made of address information of a system which is independent from the absolute address information recorded in the program area and the lead-out area.
According to this optical disk, absolute address information recorded in the program area and the lead-out area of each of the volumes is made of address information which continuously increments from an initial value without overlapping among the respective volumes and address information recorded in the lead-in area of each of the volumes is made of address information of a system which is independent from the absolute address information recorded in the program area and the lead-out area, limited address information can be allotted concentrically to the program area and the lead-out area excluding the lead-in area. Accordingly, the total amount of address information which can be allotted to the program area increases with the result that a larger amount of information can be recorded in a single optical disk. Further, since the absolute address information does not overlap among respective volumes, the function of address information for designating one address only can be maintained.
By constructing the address information recorded in the lead-in area and the absolute address information recorded in the program area and the lead-out area with mutually independent systems, even in the event that there has occurred overlapping between the two address information, the lead-in area can be distinguished from the program area and the lead-out area by a track number of Q-channel subcodes and, moreover, address information in the lead-in area and absolute address information in the program area and the lead-out area are recorded at separate positions on the Q-channel subcode format and, therefore, confusion between the two address systems will not be produced and no trouble will occur in the access operation.
The optical disk according to the invention can be constructed in such a manner that overlapping of address information in the lead-in area among the respective volumes can be avoided. Further, by forming digit of 10 of minute information in program information recorded in the program area and the lead-out area in hexadecimal, time length of 100 minutes or more can be expressed whereby the total amount of address information can be further increased and a further larger amount of information can be recorded.
Digit of 10 of minute information of address information in the lead-in area may also be formed in hexadecimal. In this case, by setting address information recorded in the lead-in area of the innermost first volume and absolute address information recorded in the program area and the lead-out area of the first volume to a value within a range (from 00 minute 00 second 00 frame to 99 minute 59 second 74 frame) determined by the CD format and also setting address information recorded in the lead-in area of the second and subsequent volumes to a value which is outside of the range determined by the CD format (i.e., from 100 minute 00 second 00 frame to F9 minute 59 second 74 frame), a reproduction device of a standard CD format cannot analyze address information in the lead-in area of the second and subsequent volumes whereby volume which the standard reproduction device can reproduce is limited to the first volume only.
In case address information in the lead-in area of the second and subsequent volumes is set to a value which is outside of the range determined by the CD format, address information recorded in the lead-in area of the second volume is made of address information which, e.g., increments continuously from the inner peripheral side of the disk and in which a final value ends with F9 minute 59 second and 74 frame.
In case 3 or more volumes are recorded in a single disk, address information recorded in the lead-in area of n-th volume (n being 3 or larger number) is made of address information which increments continuously from the inner peripheral side of the disk and in which a final value is continuous to a start address of address information in the lead-in area of n-1-th volume.
As another example of address information recorded in the lead-in area of the respective volumes, address information may be one which increments continuously from an initial value without overlapping among the respective volumes.
This optical disk can be utilized also for recording volume number identification information in a predetermined position (e.g., ZERO field of Q-channel subcodes) so that the reproduction device reads this identification information and uses it for accessing. The optical disk can be utilized also for recording data indicating that a next volume exists in a predetermined position of each volume (e.g., a main channel of the program area) so that the reproduction device reads this next volume existence information and uses it for judging whether access to the next volume should be allowed or prohibited.
There is also provided an optical disk reproduction device for reproducing an optical disk in which information is recorded in a CD format comprising a circuit for analyzing digit of 10 of minute information in address information read from the optical disk as hexadecimal. According to this optical disk reproduction device, an optical disk in which digit of 10 of minute information in absolute address information in the program area and the lead-out area or said absolute address information and address information in the lead-in area is recorded in hexadecimal can be reproduced.
For achieving the above described third object of the invention, there is provided an optical disk having a recording surface on which information prepared in accordance with a CD format is recorded and which is divided in the radial direction of the optical disk into a plurality of volumes each comprising a combination of a lead-in area, a program area and a lead-out area, information being recorded in an innermost first volume with a standard recording density determined by the CD format and information being recorded in a second and subsequent volumes on the outer peripheral side of the optical disk with a recording density which is higher than the standard recording density determined by the CD format, address information recorded in the lead-in area of the first volume and absolute address information recorded in the program area and the lead-out area of the first volume being made of address information within a range determined by the CD format and address information recorded in the lead-in area of the second and subsequent volumes being made of address information which is larger than a value determined by the CD format.
According to this optical disk, address information recorded in the lead-in area of the second and subsequent volumes is made of address information which is larger than a value determined by the CD format and, therefore, a standard reproduction device cannot analyze the address information recorded in the lead-in area of the second and subsequent volumes and hence cannot reproduce the second and subsequent volumes but can reproduce only the first volume. Accordingly, by recording main information such as a game software in the second and subsequent volumes, a standard reproduction device is prevented from reproducing the main information.
According to the CD format, address information is constructed of minutes, seconds and frames and these are expressed by 2 digit BCD code so that 99 minute 59 second 74 frame at the maximum can be expressed. By modifying a part of this format in such a manner that 4 bits prepared for expressing digit of 10 of minute information in address information recorded in the lead-in area in hexadecimal and a value of 100 minutes or more is allotted to address information in the lead-in area of the second and subsequent volumes, address information of a larger value than the range determined by the CD format can be provided while maintaining the manner of bit assignment of the CD format.
In one aspect of the invention, absolute address information recorded in the program area and the lead-out area of each of said volumes is made of address information which increments continuously from an initial value without overlapping among the respective volumes. By this arrangement, a sole address of the program area and the lead-out area can be determined. Since this address information is independent from address information in the lead-in area, limited address information resources can be exclusively used for the program area and the lead-out area so that time length allotted to these areas can be extended. Since the lead-in area can be distinguished from the program area and the lead-out area by the track number of Q-channel subcodes, no trouble will occur in operations even if address information in the lead-in area overlaps with address information in the program area and the lead-out area.
By recording information indicating existence of a next volume in each of the volumes in the form which cannot be analyzed by a standard reproduction device, the standard reproduction device can recognize only the first volume and, therefore, accessing of the standard reproduction device to the second and subsequent volumes can be prevented.
There is also provided an optical disk reproduction device for reproducing this type of optical disk comprising a circuit for analyzing address information within a range determined by the CD format and address information of a larger value than the value determined by the CD format. This optical disk reproduction device can reproduce all of the volumes of this optical disk.
The optical disk reproduction device may further comprise a control circuit for accessing an area on the outer peripheral side of the lead-out area of a currently reproduced volume to confirm existence of a next volume. According to this arrangement, the reproduction device can access each volume of this optical disk.
The optical disk reproduction device may also comprise a circuit which analyzes address information within a range determined by the CD format and address information of a larger value than the value determined by the CD format and a control circuit which reads, during reproduction of each of said volumes, the information indicating existence of a next volume and, when the information indicating existence of the next volume is available, allows access to the next volume whereas, when the information indicating the next volume is not available, prohibits access beyond the current volume. According to this arrangement, the reproduction device can access each volume of the optical disk.